By Chris Steele BSc(Hons), FCOptom, DCLP, DipOC, DipTp(IP), FBCLA

ARTICLES

TECHNIQUES

Common health conditions elderly patients are living with
Introduction

The world population is aging and people are living longer than ever before. Consequently patients are living with a wide range of ophthalmic and systemic health conditions, many of which have varying effects on vision. Gathering clinical data can be more difficult with elderly patients, compared with younger patients. Dementia, impaired hearing, visual and physical handicaps, such as impaired mobility, often limit and complicate communication and successful completion of a range of appropriate clinical investigations. Thus, obtaining an effective history demands increased clinical skills, time, extra patience, reliance on family members or carers for relevant information and maintaining good accurate clinical records that document all relevant findings and information. As a result of the patient's decreased mobility and agility, ophthalmic examination is often more time-consuming and challenging, particularly with frail elderly patients.
Undertaking an eye examination with an elderly patient, whilst maintaining the highest professional clinical standards, may require a number of adaptations to the range of clinical investigative techniques routinely used, as well as significant modifications to methods of communication. The clinician therefore should ideally be able to undertake competently a range of advanced clinical investigative techniques, where appropriate, in addition to routine clinical techniques. This is so that potential ocular signs of systemic and ophthalmic conditions that may be present are not missed. Failing to identify certain clinical signs may lead to a missed or incorrect diagnosis. Also, not being able to perform certain advanced clinical investigations may lead to otherwise unnecessary referral of patients.
Hypertension & heart disease
Hypertension is classified by the following levels of blood pressure (BP):
- Stage 1: 140/90
- Stage 2: 160/100
- Sage 3 (severe): 180/110
Blood pressure (BP) measurement can be very useful in a number of clinical scenarios and optometrists should consider undertaking, or at least be familiar with how to take BP measurements in order to improve the quality of referrals when required. The simplest way is to use a BP machine that automatically measures BP once a cuff has been inflated on the arm, just above their elbow, of the seated patient.
Diabetes

2014 2.9 million people with diabetes
2025 > 5 million
90% Type 2 Diabetes mellitus
10% Type 1 Diabetes mellitus
DR present within 20 years of diagnosis

Most diabetics undergo annual diabetic screening using digital photography. However for some diabetics, particularly frail elderly patients, or those with significant media opacities, digital imaging may not be possible. Good slit lamp biomicroscopy skills are therefore needed and competence in using a number of binocular indirect ophthalmoscopic techniques. In addition to slit lamp biomicroscopy and Volk lens indirect ophthalmoscopy, head set indirect ophthalmoscopy can be advantageous for fundus examination through dilated pupils in elderly patients with poor mobility. Even using a portable slit lamp biomicroscope may be required. Although clinically very useful in certain situations e.g. viewing disc new vessels (NVDs), relying on just direct ophthalmoscopy to examine these diabetic patients is no longer considered sufficient.
Stroke

The two main types of stroke are either haemorrhagic or ischaemic. Depending on where they occur, strokes may affect the visual pathway. The simplest method of visual field assessment in such cases is confrontation in order to pick up field defects such as homonymous hemianopia or quadrantanopia. This is a simple test often overlooked or not performed adequately enough to pick up such field defects so this should be practised routinely to maintain proficiency. Ensuring a good clinical history is also important in diagnosing stroke and looking out for other key clinical signs e.g. facial weakness, arm weakness, speech problems and time since onset of symptoms (FAST).
Malignant disease (cancers)

Malignant disease (cancer) is common in elderly patients and many may be receiving chemotherapy and/or radiotherapy. Melanoma is the most common form of ophthalmic malignant disease with 450 new cases per year. The prevalence of this condition increases with age with people over 50 years more commonly affected. It is vital that these cases are picked up early, which requires competence in thorough fundus examination - including the use of three mirror gonio lenses and head set binocular indirect ophthalmoscopy for checking the peripheral retina. Secondary metastatic tumours may also affect the eyes and these may also be picked up using routine as well as more advanced clinical techniques.
Smoking related disease (AMD)

It is always important to enquire about smoking and also to explain the consequences of smoking to patients such as nuclear sclerotic cataract and age related macular degeneration (AMD). Differentiating dry AMD from wet AMD is very important and unnecessary referrals can be avoided if the appropriate clinical investigations are properly conducted such as Volk lens indirect ophthalmoscopy macular assessment, checking for any areas of elevation signifying a retinal pigment epithelial detachment (PED) for example. In wet AMD symptoms typically include rapid onset visual loss, distortion and a central blind spot. Appropriate use of an Amsler chart at the very least or ideally having access to optical coherence tomography (OCT) to confirm the presence of sub-retinal or intra-retinal fluid can make accurate, appropriate and timely referrals much easier for subsequent treatment.
Arthritis

The two main types of arthritis include osteoarthritis and rheumatoid arthritis (RA). RA is commonly associated with iritis and 25% of RA patients have dry eyes leading to Sjögrens. Uveitis is more common in younger patients. Good slit lamp biomicroscopy and dry eye assessment skills are important e.g. tear prism height and tear break up time (TBUT), as is the ability to check for signs of uveitis (flare, cells, KPs). Occasionally with dry eyes, punctal plugs may be indicated (see clinical techniques section to view this procedure).
Parkinson's disease

This is a progressive degenerative neurological condition that affects mobility, coordination and gait. Initially a fine tremor may be noted and later this develops into a course tremor. Ocular palsies affecting the eyes are common with Parkinson’s and therefore a full ocular motility assessment is important. Despite apparently good VA, impaired visual function is common with difficulties reading. Patients may experience visual hallucinations. Blepharospasm, decreased blink rate and decreased convergence amplitudes are also often found.
Dementia
- Alzheimer’s (most common)
  - Vascular dementia
  - Lewy body dementia
  - Fronto temporal dementia
- Often undiagnosed causing:
  - difficulty sensing motion, depth & colour
  - reduced contrast sensitivity
  - Glaucoma - more rapid development
  - Increased macular drusen
The most common type of dementia is Alzheimer’s, followed by vascular dementia, then Lewy body dementia and fronto temporal dementia. Dementia is often undiagnosed causing varying disturbances of cognition which may result in difficulty sensing motion, depth, colour and contrast. Glaucoma may develop more rapidly in patients with Alzheimer’s and drusen may increase significantly at the macula so the clinician needs to be vigilant in their clinical investigations.
As the population ages, Alzheimer’s is becoming increasingly common. It has been estimated that there are 1 in 1400 of 40-65 year olds; 1 in 100 of 65-69 years olds; 1 in 25 of those over 70 and 1 in 6 of those over 80 years living with Alzheimer’s.

1. Enquiry into mental health status of patients with dementia

Careful inquiry into the mental health status of elderly patients is most important in view of the high incidence of dementia and depression among the elderly. Optometric assessment of people with dementia is often more difficult owing to their inability to concentrate, with varying levels of confusion leading to an inability to adequately comply with an eye examination. Visual perceptual problems experienced are due to neurological damage, which are often overlooked during a standard eye examination. Among the early signs of dementia in older people are the gradual loss of memory and the progression of impairment of judgment and logical reasoning. Only later in the course of the disease does disorientation become a major difficulty. If the ophthalmic examination provides any suggestion of functional cognitive impairment, it is wise for the optometrist to verify the accuracy of other aspects of clinical history with relatives and carers of the patient. By asking the patient to describe a typical day, the clinician can frequently glean important information about the patient's interests, social activities, and eating habits, for example. Delving into the daily routines of an elderly patient (particularly those with signs of dementia) gives important clues about the level of independent living an individual enjoys and helps prioritise the need for referral for interventions such as cataract surgery for example.
Any deficits, real or perceived, point to the need for more in-depth evaluation and/or a closer look at the patient's support network. Appropriate referral to an eye clinical liaison officer (ECLO) is often very helpful in such cases.

2. Modification of clinical examination techniques for patients with dementia

For optimal clinic outcomes it is recommended to always have a carer or relative present with dementia patients who hopefully can provide useful information about the individual.
Some dementia patients also may find it comforting to bring a familiar object with them that they have an affinity for, as a point of reference during the eye examination.
Charles Bonnet Syndrome

Charles Bonnet syndrome (CBS) is a common condition among people who have lost their sight, particularly the elderly. It causes people who have lost a lot of vision to see things that aren't really there i.e. visual hallucinations. Exactly how sight loss leads to hallucinations isn't really known, but research is slowly revealing more about how the eye and the brain interact. It is only natural for patients to worry, or become confused or frightened when they experience visual hallucinations. Until they know what is actually happening, elderly patients may become concerned that seeing things is a sign of a mental health problem or that they have some form of dementia. There is no single test that can be undertaken to diagnose CBS. However, it is important to reassure elderly patients that CBS is caused by sight loss only and not by any other health problem.
Glaucoma

Discussion of glaucoma is beyond the scope of this module however the advanced clinical techniques discussed here are relevant to the detection and diagnosis of glaucoma. In particular gonioscopy, applanation tonometry and pachymetry (to measure corneal thickness) in addition to non-contact tonometry (NCT) and visual field examination.
Communication techniques

Communicating accurate information and clearly and concisely explaining the outcomes of clinical investigations is an important skill when dealing with elderly patients.
Obtaining a good clinical history can be often difficult in the elderly, compared with younger patients. It can also be very challenging to achieve good patient cooperation in order to successfully undertake a range of clinical investigations. Dementia, impaired hearing and visual or physical handicaps often limit communication and the ability to cooperate well.
Obtaining an effective history and successful completion of a range of clinical investigations demands increased clinical skills, time, extra patience, reliance on family members or carers for relevant information and maintaining good accurate clinical records that document all relevant findings and information.
Dealing with elderly patients therefore requires adaptation to routine communication and clinical skills.
Always speak clearly, preferably looking straight at the patient and making constant checks that the patient understands what is happening. Ensure there is enough lighting at key points during the examination as many patients rely, to a certain extent, on lip reading to understand what is being said to them.
Many elderly patients view an eye examination as a test and worry that they may give the wrong answers. It is important to try and connect with elderly patients in an empathetic way and to reassure them that there are no “right or wrong” answers and it is up to the optometrist to interpret and conclude what is going on during the eye examination.
Ophthalmic examination may be more time consuming and challenging with frail elderly patients as they try to comply with a range of appropriate clinical investigations. Explain in simple terms what equipment or technology is being used and why. It is an important clinical skill to be able to judge just how much detail and information each individual patient requires.
Maximum use of information gleaned from relatives and carers present should always be made.
Another helpful technique with elderly patients is the increasing use of patient questionnaires or clinic record templates with prompts to ensure all relevant aspects are covered in order to obtain a complete history from patients and their relatives and carers.
As the population ages, domiciliary eye care is increasingly used to examine immobile, elderly patients in their own homes or residential care homes. During domiciliary eye examinations clinicians need to be very adaptable in terms of choosing appropriate clinical examination techniques and working in environments that are not ideal – for example poor lighting or power supplies.
Whether in a consulting room or in a domiciliary setting, it may not always be possible to undertake all the tests that are deemed clinically necessary for a variety of reasons. If a particular clinical test has not been undertaken it is important to document in the patient record what was attempted and the reasons why a test was not completed.
Portable slit-lamps may be useful particularly in a domiciliary setting or with frail elderly patients unable to adopt the correct position.
Portable slit lamp Portable slit lampHolding portable slit lampStablizing portable slit lamp4 - 4<>

Many elderly patients may not have had and eye examination for long periods of time. They often may (wrongly) assume that their failing eye sight is just part of getting older and do not realise that even simple clinical checks could make an enormous difference to their vision. In fact around 50% of the UK elderly have visual impairment due to cataract or refractive error that is correctable with optical devices such as spectacles. Demonstrating and explaining these benefits to patients in a clear, understandable, concise way is another important element of appropriate communication with elderly patients.
Medication

Accurate recording of a patient’s medications can give important information about the individual’s general and ophthalmic health and what clinical investigations may be necessary for each individual. It is increasingly common for elderly patients to be on several different medications for multiple systemic conditions, the commonest of which were described above. With regards to medication requirements: 75% of 60-75 year olds and 84% of the over 75s have more than one daily medication. Around 11% of the 65-74s and 15% >75s have five or more daily medication requirements. Many of these commonly encountered systemic drugs may have ocular side effects (e.g. raised IOP, cataract, corneal deposits). Therefore appropriate clinical investigations should be included, particularly in elderly patients to check for these.
If the optometrist is particularly concerned about any ocular side effects of a systemic drug it is important to refer the patient to their GP for further action as appropriate. It is not usually up to the optometrist to advise patients to stop any of their systemic medication without liaising with the patient’s GP first.
Refraction in the elderly

Recent studies provide evidence that optometrists from multiple-type practices in the UK are using retinoscopy less often than in the past. Retinoscopy is a vital skill to maintain as often elderly patients cannot comply with the use of an autorefractor or phoropter head during subjective refraction. Although autorefractors are now commonplace in optometric high street practice and their accuracy is validated, of course an autorefractor result is not sufficient for prescription of a pair of spectacles. Sources of error include factors such as unstable tear film, corneal irregularities, cataract and refractive surgery, media opacities and small or irregular pupils.
During refraction in certain elderly patients it is often advisable to use bracketing techniques using larger than normal steps (e.g. 1.0DS/DC instead of 0.25DS/DC) during best sphere and cross cylinder determination. Including duochrome tests routinely is of little value in elderly patients as the presence of e.g. cataract can significantly affect the results obtained. It is preferable to try and encourage elderly patients to see the maximum number of letters they can, by simply asking for example: “Can you see more letters with lens one, or two?”
Advanced clinical techniques
The following advanced clinical techniques are detailed on the 'Techniques' tab above
- Applanation tonometry
  - Goldmann (reference standard)
  - Perkins
- Icare
- ACD measurement
- Volk lens indirect ophthalmoscopy
- Goldmann 3 mirror retinal assessment
- Gonioscopy
- Head set BIO ophthalmoscopy
- Punctal plug insertion/removal
- Nasolacrimal duct syringing
Conclusions

When dealing with elderly patients it is often necessary to make various adjustments to the normal routine eye examination. Particular attention should be given to appropriate communication techniques appropriate to individual patients in order to glean the maximum information and ensure they are able to comply as best they can with a range of clinical techniques specific to their needs. Being able to confidently and competently use a wide range of advanced clinical skills and techniques is professionally very rewarding and ensures that each patient receives an eye examination to the highest clinical standards possible.

Applanation tonometry

Introduction

Goldmann applanation tonometry (GAT) is still considered the gold standard where IOP measurement is concerned. GAT accounts for normal IOP fluctuations which can occur as a consequence of ocular pulse, posture and accommodative effects. In contrast, non contact tonometry (NCT) needs repeat readings with the mean taken as the final measurement recorded. A portable alternative to slit lamp biomicroscope mounted GAT is Perkins applanation tonometry.

Goldmann applanation tonometry (GAT)

1. Calibration technique

The simplest method for checking that a GAT is correctly calibrated before each use is to:

Step 1: Assemble tonometer prism

Step 2: Turn the tonometer dial to 0

Step 3: Turn the dial to increase pressure

Step 4: Note when the tonometer head rocks forwards

Step 5: Check the dial does not exceed 3 mmHg

Figure 1 - Key for calibration check of Goldmann's applanation tonometers with 0 (0 mmHg), 2 (20 mmHg) and 6 (60 mmHg) markers

This simple technique can be used before each use. Regular formal calibration checks should also be made using the calibration bar (Figure 1). To do this:

Slot the bar holder into the slot on the side of the GAT
Note the 5 circles marked on the bar
The middle one corresponds to 0
The next ones – position 2 (20mmHg)
The outer ones – position 6 (60mmHg)
Slide the bar towards the examiner until the circle is exactly over the axis
Turn the dial and observe when the tonometer head just rocks forward for weights in position 2 and 6 (i.e. 20mmHg and 60 mmHg).

Quick GAT calibration technique - Click for audio

GAT Full calibration - Click for audio

Set on 0: Check probe tilts forwards before 2mmHg -Click for audio

Check calibration at 2 (20mmHg) - Click for audio

Check calibration at 6 (60mmHg) - Click for audio

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Tonosafe probes for infection controlHandling the Tonosafe probeInsertion of the Tonosafe prism3 - 3<>

2. Infection control

For infection control reasons, GAT is usually undertaken nowadays using a disposable Tonosafe disposable probe. A standard Goldmann tonometer cone still may be used, but if so, this MUST be disinfected with sodium hypochlorite 10% (Milton) between patients.

3. Technique

Firstly, check for active anterior (corneal) surface pathology using a slit lamp biomicroscope, by undertaking a sweep of the cornea using low magnification white light. Check that the cornea is clear. Repeat after instilling sodium fluorescein using a fluoret. Always check before and after GAT and take a photograph, wherever possible, of any surface stain caused by the procedure.

If there is high corneal astigmatism (> 4DC) adjust the cone to 43 degrees off horizontal. On the Goldmann cones there is a red marker indicating this position, which is not so for tonosafe probes.

Place the tonometer base plate in one peg, usually using the same side as the clinician’s dominant eye, so that the eyepiece is appropriately aligned with the view of the tonometer probe.

Instil a drop of anaesthetic, first checking the batch number and expiry date. Using a drug after the expiry date may mean the drug is inactive or even potentially toxic. Combination drops are a preferred option in most hospital clinics (e.g. using Lignocaine + fluorescein minims).

Position the patient comfortably on the slit lamp biomicroscope, checking their outer canthus is level with the black marker on the chin rest stand and that the patient’s forehead is touching the head rest band to keep the head steady throughout.

Check the eye level marker once more. Pre-set the force on the tonometer scale using a round number near to expected reading. Using the slit lamp joystick, bring the tonometer forward until the Tonosafe probe is within 10mm of cornea. Up until this stage hold the slit lamp joystick back against palm of the hand.

Once within ~10mm range of the corneal surface, use the thumb and first two fingers to finely move the Tonosafe head forwards, until in contact with the corneal surface.

Check from the top and side before making the final approach that the probe is lined up with the centre of the cornea.

Use the free thumb to lift the patient’s lid up against the brow – avoiding any pressure on the eye if possible.

4. Practitioner view

If one of the half rings is larger than the other, then the tonometer is e.g. either too high or too low. Adjust accordingly by moving the tonometer probe carefully in the direction of the larger ring until the half rings are of equal size (either horizontally or vertically). So if the larger ring is at the top – move the probe up. If the larger ring is at the bottom - move the probe down

Once the rings are equal – adjust the force on the tonometer scale until the inner edges of the two semi-circular rings are just touching. Re-align if necessary. If the rings are far apart – more tonometer force is required. If the rings are overlapping less tonometer force is required.

Wide bright images of the rings are caused by a tear meniscus forming around outside of tonometer cone head. Consequently this slight suction effect will give falsely lower IOP readings. This problem is commonly encountered in patients with e.g. droopy eyelids or watery eyes. If this happens, gently withdraw the tonometer probe and dry the flat end with a clean tissue and repeat.

The reading on the tonometer scale is in grammes, which must then be multiplied by 10 to give an IOP reading in mmHg. Record the technique used and time the readings were taken. Most importantly, remember to keep the tonometer probe in contact with the corneal surface for the shortest time possible to minimise the risk of corneal abrasion. Check the cornea again for fluorescein staining, taking a photo if necessary to record any staining caused. Record the depth of any abrasion with an optical section using a thin slit beam.

Advise the patient that the anaesthetic may take 15-20 mins to wear off completely.

5. Achieving accurate measurements

Source of error Effect on IOP Comment

Tear film too deep (Thick mires) Overestimates IOP Wipe prism head dry and repeat

Tear film too thin (Thin mires) Underestimates IOP Ask patient to blink and/or instil more fluorescein, and repeat

Thick cornea Overestimates IOP Correct value after pachymetry

Thin cornea Underestimates IOP Correct value after pachymetry

Corneal oedema Overestimates IOP Reassess after oedema settles

Astigmatism 'against the rule' Overestimates IOP (1 mmHg/4 D) For >3 D regular astigmatism, red mark on prism aligned with minus axis. (Not possible with tonosafe)

Astigmatism 'with the rule' Underestimates IOP (1 mmHg/4 D) As above

Post-refractive corneal surgery Underestimates IOP

Source of error	Effect on IOP	Comment
Tear film too deep (Thick mires)	Overestimates IOP	Wipe prism head dry and repeat
Tear film too thin (Thin mires)	Underestimates IOP	Ask patient to blink and/or instil more fluorescein, and repeat
Thick cornea	Overestimates IOP	Correct value after pachymetry
Thin cornea	Underestimates IOP	Correct value after pachymetry
Corneal oedema	Overestimates IOP	Reassess after oedema settles
Astigmatism 'against the rule'	Overestimates IOP (1 mmHg/4 D)	For >3 D regular astigmatism, red mark on prism aligned with minus axis. (Not possible with tonosafe)
Astigmatism 'with the rule'	Underestimates IOP (1 mmHg/4 D)	As above
Post-refractive corneal surgery	Underestimates IOP

Table 1. Corneal factors

Problem Effect on IOP Comment

Not fitting prism properly Variable Assemble prism properly

Tonometer not reading correctly Variable Check calibration

Problem	Effect on IOP	Comment
Not fitting prism properly	Variable	Assemble prism properly
Tonometer not reading correctly	Variable	Check calibration

Table 2. Instrumental error

Problem Effect on IOP Comment

Pressing on eye Overestimates IOP Ideally ask patient not to blink but if keeping eyelid open, avoid pressing on eye

Reading dial incorrectly Overestimates or underestimates IOP

Taking too many readings - Tonographic effect Underestimates IOP Can also cause corneal abrasions

Problem	Effect on IOP	Comment
Pressing on eye	Overestimates IOP	Ideally ask patient not to blink but if keeping eyelid open, avoid pressing on eye
Reading dial incorrectly	Overestimates or underestimates IOP
Taking too many readings - Tonographic effect	Underestimates IOP	Can also cause corneal abrasions

Table 3. Error techniques

Problem Effect on IOP Comment

Diurnal variation Normal (4-5mmHg) A technique called phasing i.e. multiple IOP readings during a single day, can be used

(High in morning, lower in afternoon) POAG (10-13mmHg)

Supine patient Overestimates IOP Use a Perkins tonometer

Accommodation Overestimates IOP Ask patient to look ahead into the distance

Increasing age Overestimates IOP

Arterial pulsation Overestimates IOP

Stress Overestimates IOP Reassure the patient

Squeezing of extraocular muscles Overestimates IOP ++

Squeezing of eyelids Overestimates IOP ++

Tight neckwear e.g. tie and/or collar Overestimates IOP

Valsalva manoeuvre or breath holding Overestimates IOP Ask patient to breath normally

Pre-syncopal Sudden unexpected decreased IOP Catch patient!

Table 4. Patient factors

Problem	Effect on IOP	Comment
Diurnal variation	Normal (4-5mmHg)	A technique called phasing i.e. multiple IOP readings during a single day, can be used
(High in morning, lower in afternoon)	POAG (10-13mmHg)
Supine patient	Overestimates IOP	Use a Perkins tonometer
Accommodation	Overestimates IOP	Ask patient to look ahead into the distance
Increasing age	Overestimates IOP
Arterial pulsation	Overestimates IOP
Stress	Overestimates IOP	Reassure the patient
Squeezing of extraocular muscles	Overestimates IOP ++
Squeezing of eyelids	Overestimates IOP ++
Tight neckwear e.g. tie and/or collar	Overestimates IOP
Valsalva manoeuvre or breath holding	Overestimates IOP	Ask patient to breath normally
Pre-syncopal	Sudden unexpected decreased IOP	Catch patient!

Perkins tonometry

This is a similar technique to GAT:

Insert the Tonosafe probe into the Perkins tonometer head in the same way as described previously for GAT.
Set the dial to the expected force required e.g. 1.5 or 2.0
Support the Perkins tonometer just by the hand or preferably using the extendable forehead rest. This should be adjusted to a length that allows the Tonosafe probe to be brought flat into contact with the corneal surface.
Adjust as previously described as for GAT.

BIO head set indirect ophthalmoscopy
Introduction

Nowadays slit lamp binocular indirect ophthalmoscopy (BIO) using a Volk lens is becoming almost routine in everyday optometric practice with many advantages over e.g. direct ophthalmoscopy. However, headset binocular indirect ophthalmoscopy has not really been embraced in the same way. To many it is perceived to be a difficult technique to master and used mainly by ophthalmology vitreoretinal specialists.
Headset BIO involves the use of a head band mounted light source and binocular eyepiece viewing system. Light from the illumination system is shone into the patient’s eye through a suitably powered positive lens held at its focal length from the patient’s eye (Figure 1). The reflected light from the fundus is condensed by the convex lens as it passes back to the observer’s eye pieces incorporating a pair of low powered convex lenses that enable a stereoscopic view. This condensing of the light is why the lens is referred to as a “condensing” lens. The image seen is real, but laterally and horizontally inverted i.e. upside down and back to front.

Figure 1. Head set BIO indirect ophthalmoscopy

Headset BIO is based on Gullstrand’s principle.

Figure 2. A diagramatic representation of Gullstrand's principle

There are two viewing beams (one for each of the examiner’s eyes) and one beam to illuminate the fundus (Figure 2). Using a system of mirrors (the beams can be widened to match the examiner’s interpupillary distance, a real and inverted image of the fundus can be seen (Figure 3).

Figure 3. A diagramatic representation of the BIO optics

Most of the condensing lens power is on the front, most convex surface (which is held towards the clinician). There are a variety of lenses available from 15 to 40 dioptres. The choice of lens power dictates what magnification and field of view is obtainable. With higher powered lenses, which are smaller and held closer to the patient’s eye, these give less magnification but a larger field of view.

Figure 4 – Choice of lens

A +30D lens gives about 2x magnification and a field of view approximately 65° wide. Higher powered lenses are useful in those patients with small pupils and because they give such a relatively wide field of view they are a good lens to start with for anyone new to the technique. The 20D lens is however the standard lens for general examination purposes giving around 3x magnification and a field of view ~45° wide.
Figure 5 Figure 6Figure 7 3 - 3<>
Figures 5-7 - Head set BIO equipment

Position of the patient

Fig 8

The best position for the patient is supine, however this is not possible in community practice the so the best option is to have the patient sitting on a chair in front of the examiner. This position is however not so reliable at detecting retinal tears. In peripheral gaze the pupil becomes elliptical so it is more difficult to get a clear view, and the examiner can compensate for this by tilting their head by 45 degrees. The reason for this is represented diagrammatically in Figure 9.

Fig 9
Technique
1. Preparing for headset BIO

Figures 9 and 10

The following video is relevant to the next 4 paragraphs

Place the instrument over your head positioning the illumination/ observation system centrally at the front. Adjust the top knob on the instrument’s crown head band to set the forehead band at the correct height relative to your eyes. Adjust the rear head band knob on the instrument to ensure that the horizontal band is fitting firmly around the head, but not excessively tight. Adjust the tilt of the observation system relative to the headband so that your eyes’ line of sight is perpendicular to the back surface of the eyepieces. The binocular eyepieces should be positioned so they are close to examiner’s eyes allowing for any spectacles as well.

Figure 11

Hold your thumb out in front of you at around 50cm in the centre of your field of view. Switch on the illumination, and direct the beam towards your thumb (horizontal adjustment is made by slightly twisting the headband to the left or right; if necessary also adjust the vertical direction of the light by twisting the adjusting knob on the side.
Set the inter-pupillary distance for your eyes by sliding the buttons in or out that are located on the bottom side of the eye pieces (Figure 12). Close each in turn to check that each eye can see your illuminated thumb centrally in the field of view for each eye.

Figure 12

2. Examination procedure
The following video is relevant to the rest of this section

Heat set BIO aperture settings

Figure 13 - Yellow (photophobic)Figure 14 - Cobalt blue (IVFA)Figure 15 - Large white (preferred)Figure 16 - Medium whiteFigure 17 - Small white (small pupils)Figure 13 - Diffuse white (best for beginners)6 - 6<>

Adjust the illumination rheostat to keep the brightness to a minimum for optimal patient comfort and select the aperture size (usually start with the largest of the three) with white light. Illumination can be increased if necessary later once the patient has adjusted to the brightness of the light. For smaller pupils select a smaller aperture as appropriate. Filters are available too such as red free (for blood vessels and haemorrhages) and cobalt blue (rarely – e.g. with fluorescein angiography), as well as diffuser. Figure 13 shows effects of aperture size and filters.

Hold the condensing lens between the thumb and first two fingers, with the silver or white band on the lens rim facing towards the patient and the convex lens surface facing the examiner. Explain the procedure and then ask the patient to look straight ahead over your shoulder if seated, or up to the ceiling if lying down.
Remembering to keep the brightness to a minimum for optimal patient comfort, move your head position in order that the light source is shining directly into the patient’s pupil. Observe the orange fundus reflex in the dilated pupil. If media opacities are present, these will show up as shadows in the reflex.
Ask the patient to keep both eyes open all the time to minimise any ‘doll’s eye’ phenomenon.
Then move the condensing lens into position just in front of the patient’s eye. Use the spare fingers of the hand holding the condensing lens to rest on the patient’s forehead to help steady the lens. If the patient is seated, hold the condensing lens in the left hand to view the patient’s right eye and the right hand to view the left. If the patient is lying down, the condensing lens is usually held in
the right hand when standing on the patient’s right side and in the left hand when standing on their left. This makes scleral indentation easier to undertake later on if required (this technique will not be discussed here). Sometimes it may be necessary to use the spare fingers of the hand holding the condensing lens to gently lift and hold the patient’s top eyelids up to optimise the fundus view. The other spare hand may be used to manipulate the lower eyelid as necessary.
Position the condensing lens reasonably close (2-3cm) to the patient’s eye, keeping it centred over the patient’s pupil. Ensure the blurred fundus reflex is seen through the condensing lens. Then move the lens slowly away from the patient’s eye, keeping the pupil centred in the lens and your spare fingers in contact with the patient’s forehead. The red reflex will grow to fill the condensing lens and then the fundus view will come into focus. Locate the optic disc and macula first to get your bearings and examine the posterior pole. When first learning the technique some say it may be better to go straight into viewing the retinal periphery and leave viewing the posterior until last.
If the patient is seated, to adequately view the whole fundus they should be instructed to first look up in order to view the superior fundus, then up to the right, right, down to the right, down, down to left, left and then up to the left. Typically, the extreme periphery is examined first, working toward the equator along each cardinal direction of gaze. If at any point the fundus image is lost, remove the condensing lens and check that the illumination is still centred on the pupil and then repeat the procedure as described above.
Reflections can be a nuisance which may obscure the fundus view. These can usually be eliminated by slightly moving or tilting the condensing lens as required. Avoid moving too close to the patient as this will result in loss of the stereoscopic fundus view even though the image may appear slightly larger.
When seeking to sweep their view across the retina (for example from the extreme periphery to the equator) it is vital to maintain a direct line between the observation system, the centre of the condensing lens and the patient’s pupil. This is sometimes referred to as the ‘common axis principle’.
Remember that the fundus image is upside down and back to front. So for example to view the superior retina, instruct the patient to look up, or to view the inferior retina ask them to look down. The view of the far peripheral retina will be seen in the inferior part of the image when the patient is looking up and superiorly when the patient is looking down. To overcome any blurring caused by oblique astigmatism when examining the peripheral retina, adjust the condensing lens in the same direction as the patient’s direction of gaze.
Goldmann three mirror peripheral retinal assessment
Introduction

Figure 1 - Goldmann 3 mirror lens

This is a particularly useful technique to employ e.g. in the many patients (often elderly) who report sudden onset flashes and floaters. This technique helps detect posterior vitreous detachment, directly visualising any Weiss ring present in the posterior vitreous or any signs of tobacco dust in the anterior vitreous. The technique also enables a more thorough peripheral retinal examination when looking for possible retinal tears compared with the view which is possible with Volk lens assessment only. This is crucial when determining if a PVD is uncomplicated (no retinal tear) or complicated (retinal tear(s) present). For peripheral retinal assessment a Goldmann 3 mirror diagnostic lens is the easiest and most common method to use.
Ideally the patient should have their pupils dilated, taking precautionary checks prior to dilatation (see Volk section for Van Herick technique to assess anterior chamber depth).
Technique

Dim the clinic room lights to provide ambient lighting and instil a topical anaesthetic into the patient’s eye. Check the cornea on the slit lamp microscope for any active corneal pathology.
Apply a low viscosity coupling gel such as viscotears or celluvisc 0.5% to the Goldmann diagnostic lens.

Figures 1 and 2 - Fill lens with coupling fluid

Figures 3 and 4 - Placing Goldmann 3 mirror on eye

Position the patient on the slit lamp chin rest ensuring the outer canthus is aligned with the black marker on the slit lamp head stand. Ask the patient to look up and gently hold the top eye lid against the brow. Hook the Goldmann 3 mirror lens over the bottom lid and place against the surface of the eye.
Ask the patient to look straight ahead and release the top lid so that this now rests on the top edge of the Goldmann lens. With the slit lamp viewing system and observation system aligned move the joystick forwards to focus onto the retina.

Figures 5 and 6 - Goldmann 3 mirror lens

Use the central lens to view an erect (right way up) image of the posterior pole, in particular the optic disc and macula. Adjust the slit lamp viewing system to focus on the image seen via the trapezoid mirror to view up to the equatorial retina.
With the patient continuing to look straight ahead gently rotate the Goldmann lens through 360 degrees to view all the retina in this region. When necessary hold the Goldmann lens in place momentarily with the index finger of the other hand controlling the joy stick to readjust the other lens holding hand’s fingers to continue a clockwise rotation of the Goldmann lens.
In a similar fashion next use the rectangular mirror for evaluation of the equator to ora retina.
The gonioscopy arched mirror may be use to evaluate the far peripheral retina out to the ora serrata. This is the most important Goldmann mirror to use when looking for possible retinal tears as the other more posterior retinal regions can be just as readily viewed with a Volk lens anyway.
As the Goldmann lens is rotated clockwise the height of the slit lamp beam needs to be constantly adjusted to match the position of the lens mirror.
When viewing the retina through each of the mirrors remember it is the retina directly opposite to the mirror that is being evaluated. For example, when the Goldmann mirrors are at 12 o’clock the retina at 6 o’clock is actually being viewed.
Once the examination is complete carefully remove the Goldmann lens. Sometimes light pressure on the globe is required to break the negative suction effect. Wipe away any excess coupling agent and repeat as necessary for the other eye.
Gonioscopy using Goldmann 1- or 3-mirror diagnostic lenses
Introduction

Gonioscopy is a diagnostic technique used to view the anterior chamber angle that cannot be viewed by other routine means. It is an extremely helpful diagnostic technique that can provide a great deal of clinical information. It is a relatively quick and painless procedure that is quite straightforward to perform with a bit of practice to gain initial confidence. Unfortunately gonioscopy is no longer taught in UK universities at undergraduate level. Consequently most community optometrists do not routinely undertake gonioscopy in glaucoma suspects which is a shame.
The best view of the anterior chamber angle is obtained through a Goldmann-style three-mirror lens to obtain an indirect image of the anterior chamber angle. Direct gonioscopy is rarely used nowadays and will not be discussed further here. A mirror is basically used to overcome the total corneal internal reflection. The mirror redirects light from the angle so that it exits the eye perpendicularly to the lens-air interface.
Gonioscopy may be performed for several reasons:
• To determine the mechanism of glaucoma (i.e. open or closed angle, pigment dispersion, plateau iris, etc.)
• To identify people at risk of developing angle closure glaucoma
• To monitor changes in the anterior chamber over time as clinically indicated
Technique

Position the patient comfortably on the slit lamp having first anaesthetised the cornea. Check for active surface corneal pathology and perform a Van Herick assessment of anterior chamber depth (see applanation tonometry section for details).
The diagnostic lens is placed on the eye as described above with coupling fluid to help reduce reflections. Using the three-mirror lens requires a thick coupling solution to help eliminate air bubbles (e.g. viscotears or gel tears are ideal) between the lens and the eye.
Use low magnification to identify the arched mirror in the lens. Gonioscopy needs to be undertaken in a darkened room as the pupil should be in a relaxed mid-dilated state. Use a short slit lamp beam. Shining the beam directly into the pupil should be avoided, as this may change the angle configuration, changing a narrow angle to an open angle configuration.

Start with the mirror at 12 o’clock in order to view the inferior angle first, which is often the widest and most open. Use a narrow slit beam with the illumination slightly offset to the viewing system.
Next identify the corneal optical wedge which is formed by the junction of the reflex from the corneoscleral junction and the corneal endothelium.

Figure 1 - Diagram of Corneal wedge location
Through the gonioscopy lens the thin slit of light appears as two lines: one line strikes the surfaces from the inside of the eye, crossing the iris and the angle; the other line, which looks broader and fuzzier, is created by the slit of light striking the external cornea. That second line curves in along the interface between the cornea and sclera at the limbus to meet the first line at the anterior edge at Schwalbe's line, thus making it clear where the cornea ends and the meshwork begins. So the apex of the optical wedge indicates the location of Schwalbe’s line. This is very important to locate as once you know where Schwalbe’s line is, it is much easier to locate the other structures so you understand what you are viewing.

There are seven structures that are identifiable. These are:
o Cornea
o Schwalbe’s line
o Trabecular meshwork
o Schlemm’s canal
o Scleral spur
o Ciliary body
o Iris

Figure 2 - Assess the angle

Figure 3Figure 4Figure 53 - 3<>
Basically the narrower the anterior chamber angle is, the less that is seen. If nothing is seen between the iris and cornea, the angle is closed.
To check if the angle really is closed ask the patient to look slightly in the direction of the mirror position as this will maximise the view of the angle and any structures that may be visible depending on how open it is.
The geometric width of the angle should be assessed in all four quadrants (bottom and top, then left and right). This should be estimated in degrees e.g. 10° (relatively narrow) or 40° (wide open).

The angle at the top and bottom quadrants can be assessed by simply rotating the mirror position through 180°, keeping all else the same.
To estimate the angle in the horizontal two quadrants requires some adjustments to the slit lamp illumination system:

Firstly rotate the slit beam through 90° so that it is now horizontally orientated instead of vertical.
Next realign the slit lamp viewing and illumination system. Then unclip the illumination system by pressing the lever at the bottom of the illumination system to decouple the viewing system and illumination system vertically. This is achieved once the illumination system is tilted forward at the top from its normal vertical position.
The optical wedge can then be identified in the two horizontal quadrants in the same way as before for the vertical two quadrants.
Once the angle has been assessed in all four quadrants, increase the magnification to view each quadrant for signs of e.g. pigment and synechiae.

The following grading system based on Shaffer’s system is the most commonly used:
• Grade 4 (angles between 35° and 45°): angle wide open
• Grade 3 (angles between 20° -35°): open
• Grade 2 (angles between 10° - 20°): angle closure is possible but not very likely
• Grade 1 (angles ≤10°): high risk for angle closure
• Grade 0 (0): angle closure due to iridocorneal contact.

Once the assessment is complete the gonio lens must be removed. Often a suction effect firmly holds the lens on the patient’s eye so use the following procedure (right eye):
Gently hold the lens between the thumb and first finger of your right hand. Using your left thumb, gently press on the patient’s eye through their lower lid close to the limbus to break the lens/eye seal. Then remove the lens and wipe away excess lubricant.
When the lens has been removed from both eyes check both corneas with the slit-lamp for any signs of abrasion.
Alternative lens types [audio and image slide 96] Figure caption: Gonio one-mirror lens.
One-mirror, three- and four-mirror lenses are available. In contrast to the Goldmann 1, 2 or 3 mirror lens, the four-mirror lens is a little harder to use but once mastered is easy and quicker to perform. The four-mirror lens can be applied with the patient's own tears coupling the lens to the ocular surface and it does not require any coupling agent such a viscotears. In a Goldmann three-mirror lens, only one mirror points at the angle with the other two being used to view the peripheral retina. Consequently the four-mirror lens needs to be rotated by 360° to see the entire angle. With the four-mirror lens, all mirrors show the angle, so the lens only needs to be rotated by a few degrees, hence it is quicker to use.
Icare tonometry
Introduction

Nowadays Icare tonometry is increasingly being accepted as a viable alternative to Goldmann applanation tonometry (GAT). Icare tonometry is a reliable alternative clinical technique that enables quick and accurate IOP readings in otherwise clinically challenging situations, involving patients of all ages where cooperation for a variety of reasons is limited.

Extensive bench testing and several clinical studies have clearly demonstrated the accuracy and repeatability of Icare tonometry measurements, which are very comparable to GAT.
Icare tonometry measurement is painless, as the light-weight probe touches the cornea only momentarily and some patients don't even notice the measurement. No corneal anaesthetic is required. If the device is used according to the user manual instructions, the light-weight probe cannot cause any damage to the patient's eye.
Technique
Figure 1Figure 2Figure 31 - 3<>

Six measurements are taken to provide accurate measurement results by eliminating the variations caused by operator error and heart rate. The Icare tonometer is calibrated for average central corneal thickness just like the Goldmann tonometer. For most accurate measurement results, use of any contact lenses is not recommended although soft daily disposable lenses affect the reading only slightly. In a hospital setting it is sometimes necessary to measure IOP with a bandage contact lens in situ with elderly patients for example, using an Icare tonometer. Corneal shape e.g. high astigmatism does not affect readings in the same way as GAT and no adjustments need to be made. The probe is so small that the measurements are not affected by these factors.
Infection control technique

Figure 1

Just as with GAT and Perkins, individual probes are used for each patient and then disposed of. The Icare tonometer uses single-use disposable probes and cannot be inserted incorrectly. Probes should never be cleaned or sterilized because the process and handling can damage the probe resulting in unreliable measurement results or even damage the tonometer. However, the same probe can be used for measuring both eyes in the same patient (unless one eye is infected) within a reasonably short time period.
Pachymetry
Figure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 74 - 7<>

Goldmann and Icare tonometers are calibrated for corneas of average thickness (around 550 microns). In order to know whether to apply a correction factor to IOP measurements it is important to know the patient’s corneal thickness. This can be done using a hand-held device called a pachymeter.
Anaesthetic drops are instilled and a small probe (which has been disinfected with an alcohol wipe) is gently pressed against the cornea. If necessary the patient’s lids can be gently held apart. The instrument displays the average of the readings taken, giving a mean corneal thickness measurement.
Volk lens indirect ophthalmoscopy
Introduction

This is best performed with the patient’s pupil dilated but can if necessary be performed with undilated pupils. The fundus view is however more restricted and it is not always possible to obtain a stereoscopic view. Often only a one eyepiece view is obtained and small pupils are commonly found in older patients.
Measurement of anterior chamber depth

Figure 1 - Van Herick method

Before dilating the pupil always check IOP and assess the anterior chamber angle depth (ACD) using Van Herick’s method. The depth of the anterior chamber angle measured at the temporal limbus is a good indicator for the risk of angle closure. Van Herick’s method involves using a slit lamp to estimate the depth of the anterior chamber at the temporal limbus by comparing it with the peripheral thickness of the cornea at this point. The technique should be performed in a standardised way so that results can be compared at different points in time or between patients.
Procedure
First explain to the patient what is about to happen.
• Dim the lights in the room.
• Turn the illumination column of the slit lamp to the temporal side, away from the visual axis, by 60°.
• Shine the slit lamp beam from the side at the peripheral part of the cornea and iris (the limbus), where the anterior chamber and iris are just visible. The light must be perpendicular to the temporal limbus and as close as possible to the limbus.
• View the anterior chamber from the nasal side.
• Compare the depth of the anterior chamber with the peripheral corneal thickness.
The ACD may be graded as follows:
• Grade 4 - ratio 1:1 – wide open
• Grade 3 - ratio 0.5: 1 – open
• Grade 2 - ratio 0.25:1 - angle closure possible
• Grade 1 – ratio <0.25:1 - angle occludable
• Grade 0 – angle occluded
Volk lens indirect ophthalmoscopy technique

Ideally there should be several different Volk lens powers available. High dioptre lens powers (e.g. 128D or 90D) give a wider field of view, whereas lower powered lenses (e.g. 66D) provide a more magnified image of a section of the retina e.g. the optic disc or macula.
Technique

First align the slit lamp biomicroscope’s illumination and observation system and centre the beam over the patient’s pupil. Ensure the patient’s head is positioned comfortably on the slit lamp chin rest. Adjust the height of slit lamp beam until it is at least the diameter of the pupil.
Hold the viewing Volk lens between thumb and first finger and focus the slit lamp biomicroscope viewing system on the patient’s iris. Hold the lens just in front of the patient’s eye (working distance varies. between 6-12 mm depending on lens power used), resting the bent elbow on the Volk lens box for comfort and stability during fundoscopy.
Ensure the slit lamp beam is aligned through the Volk lens into the patient’s pupil and ask the patient to look at your ear to ensure they are looking roughly straight ahead.
Hold the Volk lens between the index finger and thumb, resting the second and third fingers on slit lamp head band. (If the lens is held further away this reduces the field of view and it will not be binocular.)
Then, holding the joystick gently against the palm of the hand, move the slit lamp back away from the eye to focus on the fundus. Check the fundus is seen is with both eyes in order to view a stereoscopic image. Fine adjustments can then be made to the slit lamp position and focus by making small movements of the slit lamp joy stick with the thumb and first two fingers.
Broaden the beam as required and move the slit lamp microscope to scan across the fundus. First try to locate the optic disc, which then acts a reference point thereafter. Remember that the image viewed is upside down and back to front. Move towards the patient’s nose to see macular area and move away from nose to see temporal retina. Ask the patient to look in 8 cardinal directions of gaze to view the entire fundus. When the patient is looking off-axis tilt the Volk lens away from the axis as needed.
When first learning this technique try turning the record card upside down first before recording fundus findings as they were seen.
Nasolacrimal duct syringing
Nasolacrimal duct syringing – equipment

Nasolacrimal drainage system

Procedure
Punctal plug insertion
Punctal plug insertion
- Consider dissolvable plugs initially
- Apply anaesthetic
- Assess size of puncta
- Smart plugs expand with body heat
- Dilate puncta if necessary
- Biofeedback – less tears if less drainage
Punctal plug procedure
- Use gauge first – determine plug size
  - Enters tightly under pressure
  - Resists removal on extraction
  - Move side to side to check - elasticity
- Lubricate the plug
- Dilate puncta
- Push plug into puncta – corkscrew action
- Use curved tweezers to remove